Recently, the amount of data transmitted over a wireless communication network is swiftly increasing because various devices appear and spread which require high data transmission and machine-to-machine communication, such as smart phones or tablet PCs. There are attention attracting technologies such as cognitive radio (CR) technology and carrier aggregation (CA) for effectively using more frequency bands, multi-antenna technology for raising data volume within a limited frequency.
Further, wireless communication networks are evolving such that the density of accessible nodes around users increases. Here, the “nodes” means antennas or antenna groups that are spaced apart from each other at a predetermined interval or more in a distributed antenna system (DAS), however is not limited thereto and rather may have a broader meaning. That is, the node may be a macro base station, a picocell base station (PeNB), a home base station (HeNB), an RRH (remote radio head), an RRU (remote radio unit), a relay station, and a distributed antenna (group). The higher density of nodes a wireless communication system has, the higher system performance the wireless communication system may show due to inter-node cooperation. That is, than when each node operates without cooperation with an independent base station, when each node is managed by a control station in light of transmission and reception and is operated as an antenna or antenna group for one cell, even better system performance may be achieved. Hereinafter, a wireless communication system including a plurality of nodes is referred to as a multi-node system.
Inter-node cooperated transmission (CoMP) may apply to such multi-node system. The cooperated transmission means a transmission scheme in which a plurality of nodes attends signal transmission and reception for the same terminal. The cooperated transmission schemes include joint processing and scheduling coordination. The joint processing refers to a scheme in which a plurality of nodes simultaneously participates in signal transmission and reception and includes JT (joint transmission) and DCS (dynamic cell selection). The scheduling coordination refers is to a scheme in which a plurality of nodes participates in signal transmission and reception for the same terminal at different times by scheduling and includes CS (coordinated scheduling) and CB (coordinated beamforming).
In case such cooperated transmission is applied to multi-node systems, there is a need for a method of feeding back channel status information of the terminal.